1//===- DWARFDebugAranges.cpp ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
10#include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
11#include "llvm/DebugInfo/DWARF/DWARFContext.h"
12#include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
13#include "llvm/Support/DataExtractor.h"
14#include <algorithm>
15#include <cassert>
16#include <cstdint>
17#include <set>
18
19using namespace llvm;
20
21void DWARFDebugAranges::extract(
22    DWARFDataExtractor DebugArangesData,
23    function_ref<void(Error)> RecoverableErrorHandler) {
24  if (!DebugArangesData.isValidOffset(0))
25    return;
26  uint64_t Offset = 0;
27  DWARFDebugArangeSet Set;
28
29  while (DebugArangesData.isValidOffset(Offset)) {
30    if (Error E =
31            Set.extract(DebugArangesData, &Offset, RecoverableErrorHandler)) {
32      RecoverableErrorHandler(std::move(E));
33      return;
34    }
35    uint64_t CUOffset = Set.getCompileUnitDIEOffset();
36    for (const auto &Desc : Set.descriptors()) {
37      uint64_t LowPC = Desc.Address;
38      uint64_t HighPC = Desc.getEndAddress();
39      appendRange(CUOffset, LowPC, HighPC);
40    }
41    ParsedCUOffsets.insert(CUOffset);
42  }
43}
44
45void DWARFDebugAranges::generate(DWARFContext *CTX) {
46  clear();
47  if (!CTX)
48    return;
49
50  // Extract aranges from .debug_aranges section.
51  DWARFDataExtractor ArangesData(CTX->getDWARFObj().getArangesSection(),
52                                 CTX->isLittleEndian(), 0);
53  extract(ArangesData, CTX->getRecoverableErrorHandler());
54
55  // Generate aranges from DIEs: even if .debug_aranges section is present,
56  // it may describe only a small subset of compilation units, so we need to
57  // manually build aranges for the rest of them.
58  for (const auto &CU : CTX->compile_units()) {
59    uint64_t CUOffset = CU->getOffset();
60    if (ParsedCUOffsets.insert(CUOffset).second) {
61      Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
62      if (!CURanges)
63        CTX->getRecoverableErrorHandler()(CURanges.takeError());
64      else
65        for (const auto &R : *CURanges)
66          appendRange(CUOffset, R.LowPC, R.HighPC);
67    }
68  }
69
70  construct();
71}
72
73void DWARFDebugAranges::clear() {
74  Endpoints.clear();
75  Aranges.clear();
76  ParsedCUOffsets.clear();
77}
78
79void DWARFDebugAranges::appendRange(uint64_t CUOffset, uint64_t LowPC,
80                                    uint64_t HighPC) {
81  if (LowPC >= HighPC)
82    return;
83  Endpoints.emplace_back(LowPC, CUOffset, true);
84  Endpoints.emplace_back(HighPC, CUOffset, false);
85}
86
87void DWARFDebugAranges::construct() {
88  std::multiset<uint64_t> ValidCUs;  // Maintain the set of CUs describing
89                                     // a current address range.
90  llvm::sort(Endpoints);
91  uint64_t PrevAddress = -1ULL;
92  for (const auto &E : Endpoints) {
93    if (PrevAddress < E.Address && !ValidCUs.empty()) {
94      // If the address range between two endpoints is described by some
95      // CU, first try to extend the last range in Aranges. If we can't
96      // do it, start a new range.
97      if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
98          ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
99        Aranges.back().setHighPC(E.Address);
100      } else {
101        Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
102      }
103    }
104    // Update the set of valid CUs.
105    if (E.IsRangeStart) {
106      ValidCUs.insert(E.CUOffset);
107    } else {
108      auto CUPos = ValidCUs.find(E.CUOffset);
109      assert(CUPos != ValidCUs.end());
110      ValidCUs.erase(CUPos);
111    }
112    PrevAddress = E.Address;
113  }
114  assert(ValidCUs.empty());
115
116  // Endpoints are not needed now.
117  Endpoints.clear();
118  Endpoints.shrink_to_fit();
119}
120
121uint64_t DWARFDebugAranges::findAddress(uint64_t Address) const {
122  RangeCollIterator It =
123      partition_point(Aranges, [=](Range R) { return R.HighPC() <= Address; });
124  if (It != Aranges.end() && It->LowPC <= Address)
125    return It->CUOffset;
126  return -1ULL;
127}
128